This invention relates to a camera that has a parking mechanism for ensuring that the visual exposure indicator (VEI) of an Advanced Photo System (APS) film cassette is in the "parked" or "x" position when the film cassette is removed from the camera and exposed to light.
Advanced Photo System film cassettes, as shown in FIG. 1, have a visual exposure indicator disposed in the bottom of the cassette. The visual exposure indicator includes an icon and the plastic covering over the bottom of the film cassette. This visual exposure indicator has four positions, a circle, a half circle, an "x" and a rectangle, as shown in FIG. 1. Each of the shapes, the circle, half circle, "x" and rectangle are defined as an opening in the plastic covering disposed in the bottom of the cassette. The icon is disposed inside of the cassette and moves relative to the openings, so that it can be seen through one of the openings. When visible through one of the openings, the icon is visible as the defined shape of the respective opening.
The status of the film in the film cassette is indicated by the position of the icon relative to the openings. If the icon is visible through the circle, it indicates that the film has not been exposed and the film cassette is ready for use. When visible through the half circle, the icon indicates that the film has been thrust from the cassette or partially exposed. The "x" indicates the exposed or "parked position" in which the film has been rewound into the cassette. Finally, the rectangle indicates that the film has been processed or developed. The VEI of the cassette is beneficial because the status of the film can be quickly obtained by examining the VEI. Therefore, it is important to ensure that the VEI always indicates the proper status of the film. For example, if the VEI was in the wrong position, it may be mistakenly understood that the film has not been completely exposed when it has.
The icon of the VEI operates with the spindle of the film cassette. By rotating the spindle, the VEI is moved to the various positions. In order to move the icon to the "x" position, the trailing edge of the film must be rewound into the cassette after the light lock door of the cassette has been closed. Potentially, the VEI could remain in the half circle position when the trailing edge of the film enters the cassette and the light lock door is closed. The spindle must be rotated a further distance after the closing of the light lock door to ensure that the VEI moves to the "x" position.
Motorized APS cameras typically ensure the spindle is rotated this further distance by detecting the film is fully inside of the cassette 14 or the closing of the light lock door and then rotating the spindle a predetermined rotational distance that corresponds to the VEI moving to the "x" position. Detection can be done with a film sensor that detects movement of the trailing edge of the film into the film cassette. Alternately, a mechanism that operates with the light lock door and senses the movement of the light lock door to the closed position can be used. Since the camera is motorized, circuitry can be used to ensure the motor rotates the spindle this predetermined rotational distance after the light lock door is closed.
In order to reduce the cost of APS cameras, its desirable to develop manual APS cameras. These cameras are termed "manual" because they would not have a motor for moving the film. Rather, they would have a mechanism, such as a thumb wheel or a crank, that can be manipulated by a camera user to manually move the film within the camera. Since such a camera does not have a motor, the camera user must rotate the spindle after the closing of the light lock door to ensure that the VEI moves to the "x" or parked position. Potentially, the camera user could drive the trailing edge of the film into the film cassette 14 and close the light lock door and stop further movement of the film. At this point, the VEI may still be in the half circle position. Further, the camera user could then remove the cassette from the camera. A later inspection of the film cassette would incorrectly indicate that the film has not all be exposed. Thus, there is a need for the camera user to know when the VEI has moved to the parked position.
This invention relates to a camera that has a mechanism for ensuring that the VEI of an APS film cassette is in the proper position after the film has been exposed and rewound into the film cassette. This invention also relates to such a mechanism that can be employed with a manual APS camera.